In the last few years an extraordinary emphasis has been placed on the design and use of PET cameras for small animal studies, for example, to aid in the development of human gene therapies by imaging transgenic animals such as mice. Although, such techniques have an extraordinary potential for both clinical and basic biomedical science applications, its full realization is severely hampered by the expense, complexity and physical limitation of crystal detectors widely used in today's cameras. In particular, crystals are costly and very difficult to segment to the desired 1 mm level. Furthermore, depth of interaction error in the 1 cm or greater crystal depth required causes severe degradation of off-axis resolution. This project seeks to develop enhanced high resolution PET through the highly novelapproach of the lead walled straw (LWS). In Phase I, feasibility of application of this high energy physics spin off technology has been proven, and in fact it has been demonstrated that considerably enhanced imaging characteristics can be achieved. A 2 mm LWS modular unit has been developed which has produced 1.0 mm FWHM axial spatial resolution. When utilized in ring arrays, such a module will produce a reconstructed volumetric spatial resolution of less than 2 ul, which is a factor of 8 improvements compared to the best commercial camera. Furthermore axial sensitive field of view can be readily extended to as large as 20-40 cm, and very high sensitivity can be achieved at modest cost. In Phase II, a promising modular detector design will be fully implemented and a custom electronics readout system will be developed, facilitating low-cost construction. A small animal PET camera will then be developed with performance that substantially exceeds that of current commercial systems for murine and other small animal imaging. In Phase III, this camera will be developed into a commercial product, which is expected to substantially aid in this important research field.